The present invention relates to a method of and a device for production .Iadd.of .Iaddend.hydrocarbons, such as oil.Iadd., natural gas .Iaddend.and the like.
It is known to produce oil .[.by introducing into it gas so as to form an oil-gas.]. .Iadd.or other hydrocarbons in situations where oil or other liquids are combined with natural gas or other gases to form a liquid-gas .Iaddend.fluid which is lifted in a production pipe. The resulting flow is a flow of two interacting phases, a gas phase and a liquid phase. Depending on a diameter of the production pipe, a gas factor or a gas quantity dissolved in a mass unit of liquid, physical characteristics of gas and liquid, speed of the gas phase relative to the liquid phase, an exchange of the motion quantity between the phases and therefore a share of gas phase energy spent for displacement of the liquid phase can substantially change during the process of flowing of the two-phase medium. Due to the changes in the structure of the two-phase flow during the process of flowing and redistribution of energy of the gas phase used for the displacement of the liquid phase and for the displacement of the gas phase itself, it is possible that a corresponding energy share of the gas phase is insufficient for displacement of the liquid phase. This is characteristic for the case when the energy of the gas phase is the only source of energy for displacement of the liquid phase. This case is typical.Iadd., for example, .Iaddend.for oil wells when the natural energy of the formation is composed of a potential energy of oil which is .Iadd.contained .Iaddend.under pressure from rock, ground water, and potential energy of hydrocarbon gas dissolved in oil, which .[.are .]. .Iadd.is .Iaddend.transferred into the gas phase when the pressure in the fluid becomes lower than the saturation pressure. Oil which is lifted in a well to a certain height by the pressure of rock ground water, .Iadd.and .Iaddend.gravitational energy, can move further only due to the energy of gas dissolved in oil and transferred to the gas phase at a certain level in the well when the hydrostatic pressure in the oil column becomes lower than the saturation pressure. During movement of the fluid to a well-head with reducing pressure the quantity of gas emerging from oil is increased and the structure of the flow changes. An increase of the gas quantity transferred from the dissolved condition into the gas phase and correspondingly of its speed during movement to the well head leads to the situation that in a portion of the well which adjoins the .[.well head.]. .Iadd.well-head .Iaddend.an annular mode of flow is formed, when the oil forms a film extending along the pipe wall while a gas nucleus contains liquid drops. Therefore only a small fraction of the gas phase energy is used for displacement of the liquid to the well-head and practically the well yield is equal substantially .Iadd.to .Iaddend.zero. The evolution of the flow structure in the well is such that during the movement of fluid to the well-head the pressure and quantity of gas .[.emerge.]. .Iadd.emerging .Iaddend.from the liquid is reduced and the speed of the gas phase relative to the liquid is increased. As a result the liquid and gas phase have a tendency to separate from one another. During this process a corresponding fraction of the gas phase energy used for the displacement of liquid to the well-head is reduced.
When the well is in the annular mode, its efficiency coefficient or in other words a ratio of the gas phase energy actually used for the liquid displacement to all energy of the gas phase which can be used for the liquid displacement, reduces substantially .Iadd.to .Iaddend.zero. Even when the well operates in a fountain mode, the efficiency coefficient can not be high since the structure of the flow near the well-head #is such that the gas phase occupies the main .[.fraction.]. .Iadd.portion .Iaddend.of the space .Iadd.available .Iaddend.for the fluid flow and the quantity of the entrained liquid is relatively low. The low efficiency coefficient leads to an accelerated degasification of formation and as a result to a conversion of the well to a mechanized .[.expansive.]. .Iadd.expensive .Iaddend.production method.